Sequential fuel control

ABSTRACT

A ROTARY DISTRIBUTOR VALVE SEQUENTIALLY OPERATED IN RESPONSE TO POWER LEVER POSITION AND FILL FLOW INTERCONNECTS METERED FUEL FROM A MAIN FUEL CONTROL AND BURNER SEGMENTS OF A POWERPLANT ONLY AFTER THE SEGMENTS AND THEIR INTERCONNECTING FLOW LINES ARE FILLED WITH FUEL.

' Jan. 5, 1971 D. EQANscHuTz ETAL 3,552,123

A' SEQUENTIAL FUEL CONTROL l Filed June 26. 1969 FUEL CONTROL l /M /a 60 E 2 llllll( Il P= PRESSURE ATTORN EY United States Patent Office 3,552,123 SEQUENTIAL FUEL CONTROL Donald E. Anschutz, Wilbraham, Mass., and Kail L. Linebrink, Bloomfield, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed June 26, 1969, Ser. No. 836,827 Int. CL F02g 1/06,l F02k 3/ 10, 3/04 U.S. Cl. 60-39.28 9 Claims ABSTRACT F THE DISCLOSURE A rotary distributor valve sequentially operated in response to power lever position and fill flow interconnects metered fuel from a main fuel control and burner segments of a powerplant only after the segments and their interconnecting tiow lines are filled with fuel.

CROSS-REFERENCE TO RELATED APPLICATION This invention is related to an invention entitled Sequencing Mechanism for a Fuel Control, application Ser. No. 836,774, filed by G. A. Fisher and C. F. Stearns of even date and assigned to the same assignee.

BACKGROUND OF THE INVENTION This invention relates to fuel controls and particularly to a rotary distributor valve and sequencing control therefor admitting fill flow to a plurality of nozzles in a combustion chamber in response to power lever and fill flow parameters.

As is well known in certain types of jet engines, it is customary to mount a plurality of nozzles at various locations in the combustion section to optimize combustion efficiency and is desirable to sequentially feed these nozzles with fuel in a predetermined pattern such that certain segments of nozzles are fed with fuel prior to feeding the other segments. Thus, not only does this control provide proper sequencing of fuel flow to the nozzles, it also provides means for controlling the sequence so that fuel flow may be stopped and/or reversed at any number of scheduled segments. To this end the sequence segment control allows scheduling of any number of segments in such a manner that metered flow is not allowed to enter a segment until it is filled with fuel.

SUMMARY OF INVENTION A primary object of this invention is to provide a segment sequence control for delivering fuel to combustion sections of a turbine type of powerplant subsequent to filling the individual nozzles with fuel. It is to be understood that combustion section is defined as being a nozzle located in any station of the engine where combustion occurs.

A still further object of this invention is to provide a rotary type of distributor valve operable in response to BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration, partly in sectional, showing the details of this invention.

FIG. 2 is a schematic illustration showing the sequence control distributor valve connected to the segments in the burner section of a bypass of a jet engine partially shown.

3,552,123 Patented Jan. 5, 1971 DESCRIPTION OF THE PREFERRED EMBODIMENT As can be seen in FIG. 2, a jet engine generally indicated by numeral "10, only a portion being shown, includes a `ducted fan section 12 in which is disposed a series of nozzle segments 14 which in this instance takes the form of annular rings varying in size and disposed at different stations within the engine, connected to the distributor valve 16 through the interconnecting lines 18, 20, 22, 24, 26, and 28. Obviously, there are as many lines as there are nozzle segments` and the number and pipes of nozzle segments not being limited but depending rather from the design criteria of the particular engine. Distributor valve 16 comprises a rotary valve element 19 having a central bore 21 formed therein communicating with a radial passage 32 adapted to selectively register with a plurality of circumferentially spaced ports 34, 36, 38, 40, 42, and 44. In addition, an arcuate slot is formed ther-ein having sufficient area to span the entire arc of ports including 34 through 44, inclusively. Thus, rotation of valve element will first place radial passage 32 in line with 34 for receiving fuel from a separate source to be described herenbelow prior to communicating with passage 50` defined by the arcuate slot 52 formed in the rotary valve element. Rotation of the valve element to the next port 36 places in communication the port 34 and the annular space 50 to which is fed metered fuel as will be described hereinbelow.

Therefore, lfrom the foregoing, it is apparent that selectively positioning th-e radial passage 32 to register with radial passages 34 through 44 inclusively will first place fuel from a separate source to fill the lines communicating with the respective ports prior to placing the metered fuel evidenced in the chamber defined by the arcuate slot 52 for delivering metered fuel to the respective segments of the engines combustion chamber. As noted from FIG. 1, metered fuel is admitted to the distributing valve through drilled passage y60 and into chamber 50 for selectively being admitted to the various flow lines interconnecting ports 34 through 44 inclusively and the burner segments.

The fill flow which is fuel pressurized by the fuel pumping system is admitted to fill fiow shutoff valve via line 72, valve 70 serving to assure that the fuel is not admitted into the system until actuated by the latching mechanism generally indicaed by reference numeral 144 consisting of valves 174 and 143. As noted from FIG. l valve element 74 moves against the compression spring 76 and the pressure in chamber 71 delivering fuel to the fill flow throttle valve generally indicated by numeral 78 Via line 80 and pressure regulator generally indicated by numeral 82. The shutoff valve will be described in more detail hereinbelow. Th-e pressure regulator serves to maintain the pressure drop across the metering orifice 84 at a constant value, which is dictated by the force of spring 86. The valve operates by sensing upstream and downstream pressure across metering orifice 84 by admitting upstream pressure to act on one face of valve element 88 and downstream pressure to act on the opposing face of element 88, pressure being admitted thereto respectively via passages 90 and 92. Since the area is equal, the force created by spring 86 acting in concert with downstream pressure urges valve element 88 to open valve metering element 92 with respect to the valve seat 94. This force is counteracted by the force acting on the underside of valve element 88. When the total force of the pressure on the upperside of valve element `88 and spring 86 counterbalance the force acting on the underside, the pressure drop (AP) across metering orifice 84 Will be equal to the force of spring 86. Any deviation from the balance will adjust valve element 88 until the AP is returned to its selected vaille.

Fuel admitted into orifice 84 passes through an axial drilled passage 96 formed in the iill flow throttle valve 98 and communicates with radial passage 32 formed in the rotating distributing valve element 19.

From the foregoing it is apparent that the rotary distributor valve element -19 serves to ll the one line interconnecting the burner segment with fuel delivered from one source and then proceeds to fill the next adjacent segment, which fuel being metered from the main fuel control, shown in blank, enters the fuel section to deliver metered fuel to that particular connecting segment ring just lled. By contouring orice 84 as shown, it is possible to select the rate at which each segment will ll. It is understood, as is obvious to one skilled in the art, that the outer window (orifice) cooperating with the inner window has a fixed metering area and the total metering area will be dictated by the portion of the windows that is exposed to the fuel ow.

The next portion of the description will describe the actuation of the rotary distributor valve 19. As noted from FIG. 1, the till ow throttle valve 98 is connected to the rotary distributor valve 19 by an axial hollow shaft 100. Shaft 100 carries pinion gear 102 which is in mating relation to the rack gear 104, the details of both being eliminated for the sake of convenience as any means of actuation will fall within the purview of this invention. The rack gear 104 is made integral with the connecting shaft 106 interconnecting the pistons 108 and 110. Fluid admitted to these pistons serves to position them with a consequential movement of the rack 104 and a likewise rotary movement of the distributor valve 19. This movement is made in response to the power lever generally indicated by numeral 112 which serves to control the power lever servo 136 and the cooperating cam 172 which, in turn, schedule the segments in a predetermined manner but assuring that the ll is manifested before the various burner segments are connected to the metered fuel. Power lever adapted to be positioned for admitting fuel to the segments is connected to cam 114 via the schematically illustrated connection 116. Cam 172 is adapted to schedule one or all of the segments in sequential order and by moving it to the extent of its travel which will be the high point of the node, follower 118 is forced upwardly causing the pilot valve 120 to move in an upward position. As would be obvious to one skilled in the art, cam 172 can be used to adjust the fuel control so as to properly schedule metered fuel flow with the actuated segments. The lands on valve 120` uncover ports -122, 124 and 126 for communicating high pressure line 128 with line 130 for admitting pressurized iluid into chamber 132 of piston actuator 134. However, piston 136 will remain stationary until Huid present in chamber 148 formed on the back side of piston 136 is drained. Draining of this chamber is etfectuated by latching mechanism 144. As can be seen from the drawing, latching mechanism 144 is connected to the lever 146 and serves to open chamber 148 to drain by positioning valve element 142 downwardly. Hence, piston 136 will remain stationary notwithstanding the admittance of pressurized fluid in chamber 132 until line 152 is connected to drain via line 140, pilot valve 120, and drain connection 138.

The latching mechanism 144 is controlled by ll sensor generally indicated by numeral 156. The ll sensor measures the iluid being admitted to the various fill lines and responds to the uid in the line communicating with the source of till fluid. While the particular means for sensing when a segment line is lled does not form a limitation to the invention, in this instance the lill sensor measures the pressure drop across orifice 84 and when that approaches Zero, the ilapper valve 158 will shut off the llow from orice 160 to build up the pressure downstream of restrictor 162 which ultimately is admitted into actuator 164 via connecting line 166. Thus, when the pressure drop across orifice 84 is at zero, pressure is admitted behind piston 168 urging it against spring 171 in a downward direction for positioning lever 146 downwardly and with a like movement of valve element 142 being connected thereto by the pin connection 170. This movement interconnects line 152 with line 140 for draining chamber 148. Piston 136 is then urged upwardly and by virtue of the rack and pinion connection generally indicated by numeral 173 causes the power lever servo cam 172 to rotate and position valve element 174 upwardly. Lever 146 abuts against the projecting pin 176 and since it is moved upwardly likewise lever 146 also moves upwardly repositioning valve element 142 to the closed position and hence latching the system until the next segment is filled.

As noted, the till sensor 156 consists of piston 180 having one surface exposed to pressure upstream of orilice 84 via line 182 and the other surface to pressure downstream of orifice 84 via line 184. Hence, the pressure acting across orice 84 and the force of spring 181 is felt by piston and moves flapper 154 relative to orifice 160 by virtue of the connecting rod 188. High pressure discharging from 160 is normally dumped to drain (i.e., pump inlet) via port so that closure of iiapper valve 158 builds up pressure downstream of orice 162 disposed in line 192 which in turn is transmitted to chamber 164 via line 166 and the Most selector valve 194.

Thus, from the foregoing, it is apparent that the admittance of pressure into chamber 132 and the dumping of pressure from chamber 148 permits piston 136 to move axially for rotating cam 172. The cam motion is picked up by follower 200 suitably attached to the lever 202 which is also pinned to the pilot valve 120 by pin 204. This feeds back the signal to the pilot valve to return it to its null position such that the lands 122, 124, 126 are in line-on-line with the respective ports which will occur only when the signal scheduled by the pilot lever 112 as seen on cam 114 is matched by the number of segments actuated. Thus if the power lever is positioned to fill the six segments, then the null position will be reached solely when the six segments are filled.

In addition, the motion of cam 172 is also picked up by follower 208 which is suitably connected to fulcrumed lever 210 having one end bearing against spring 212 disposed on the top surface of pilot valve 214. Pilot valve 214 serves to position pistons 108 and 110 for controlling movement of the segment distributor valve 19, This is effectuated by applying a pressure signal to chamber 216 via drilled passage 218 and line 220. This is accomplished by controlling the pressure drop across fixed restriction 222 disposed in line 220 which is in communication with regulated pressure discharging from the pressure regulator indicated in blank by reference numeral 224 which is fed by pump 226 in communication with reservoir 228. As noted from FIG. l, the branch line 230 downstream of xed restriction 222 feeds into chamber 232 which has disposed therein bellows 234. Formed on the free end of the bellows and centrally disposed thereof is orice 236 which is in proximity to the projection 238. Movement of the bellows 234 positions orifice 236 relative to projection 238 for effectuating closure thereof. The bellows is controlled by the push rod 240 which is urged against cam 242 attached to the hollow shaft 100. Rotation of the hollow shaft 100 rotates cam 242 to position push rod 240 relative thereto and for each position of came 242 there will be a corresponding position of orifice 236 and likewise there will be a corresponding presssure in chamber 216 for positioning the land of spool 214 relative to the various ports. Thus, high pressure admitted into port 250 is either directed to line 252 or 254 depending whether the spool has beeen moved upwardly or downwardly. If 252 is connected to high pressure, then 254 is connected to drain via line 256. Conversely, if high pressure is admitted to 254, then line 252 is connected to drain via line 258. Lines 252 and 254 are in communication with the ends of pistons 110 and 108 respectively, for effectuating movement thereof. The force of the pressure acting on the end of spool 214 created by the pressure in chamber 216 is counteracted by the force produced by spring 212. When these forces are balanced, no movement of pistons 108, 110 will occur. Accordingly, for each position of rotary distribution valve 19 there will be a corresponding position of cam 242 and a likewise corresponding position of lever 210 and pilot valve 214 will be at the null position.

To effectuate closure of the various segments, the pilot lever is returned to its original position rotating cam 114 to the lower point imparting an unbalance to lever 202 with a consequential downward movement of pilot valve 120. This positions lands 122, 124, and 126 downwardly to uncover the various communicating ports for applying high pressure from line 128 to the Most selector valve 194 via line 260. This moves the ball 262 downwardly to block off flow from line 192. Piston 168 moves downwardly for disarming the latching mechanism 136 by a consequential downward positioning of valve element 142. High pressure is then applied from line 266 into line 140 by land 126 for applying high pressure into chamber 148 via the latching valve 136 and line 152 urging piston 136 downwardly for rotating the power lever servo cam 172 by the rack and pinion mechanism generally indicated by numeral 173. Pilot valve 120 is continuously urged in a downward direction by action of spring 272. Obviously, rotation of cam -172 in a downward direction will cause an unbalance on spring 212 by the movement of lever 210. As the load decreases by rotating lever 210y counterclockwise, the pilot valve will move so that the lands are positioned to communicate the pressure behind piston 110 and the pressure behind piston 108 so that it will move in a decreasing direction. It will continue to move until the scheduled signal imposed by cam 114 is satisfied. Any number of nozzles can be shut off in a descending manner. Thus, movement of power lever if advanced, initiates the various segments sequentially in an ascending order and if retracted, turns off any given number of segments in a descending order.

OPERATION OF THE SEQUENCE SEGMENT CONTROL Assume the pilot is calling for the full number of segments to be turned on, he will advance the pilot vlever to the full open position. This, in turn, rotates cam 114 to the high point creating an unbalance on fulcrum lever 202 for positioning the pilot valve 120. This, in turn, admits high pressure servo fiuid into the pilot lever servo piston 136 for urging it upwardly. Since chamber 148 is filled with fluid, the piston will not move until this fluid is dumped. Dumping of fluid from chamber 148 is effectuated by actuating the latching mechanism 144 by unseating valve 142 is response to the fill sensor 156 sensing fill line 96 by measuring the pressure drop across orifice 84. When the line is filled, i.e., when the AP across 84 is substantially zero, and this will occur since the pressure drop is being felt across the nozzles when the line is filled, this signal is transmitted to latching servo 164 by closing off the fiapper orifice 160 with fiapper element 158. As noted from FIG. l, the pressure drop is measured across the fill flow shutoff valve 74 and in line pressure regulator 82 inasmuch as this is an indication of the AP across orifice 84. As would be obvious to one skilled in the art, any other pressure indicative of AP across orifice 84 can be utilized. This, in turn allows the pressure in line 192 to increase and this pressure is in turn felt on the back side of piston 168 being in communication with line 166- which is in communication with line 192. Piston 168 moves down forcing lever 146 to pivot clockwise about pin 176 therefore carrying valve 142 downwardly to open up line 140 to line 152. Since land 126 has moved upwardly, drain line 139 communicates with line 140 for draining the fluid in chamber 148, and permitting the piston 136 to move upwardly for rotating cam 172 allowing lever 146 which is balanced by spring 280 to move to its latching position. The metering land of valve 284 serves to assure that the shutoff valve 74 is closed when the filling process is completed. Hence, once the line is filled with fuel from a separate source, says directly from the pumps, the distributor valve 19 is allowed to rotate so as to place metered fuel from the main fuel control in communication with the segment just filled. The rotation of the metering Valve then places the radial passage 32 of distributor valve 19 in communication with the next line 36. Line 36 fills up in a similar manner and when it is completely filled, the pressure drop across 84 again becomes zero reactivating the latching mechanism 136 to allow the distributor valve to move in the manner just described above. Of course, the movement of the distributor valve is dictated by the position of cam 172 which controls the pilot valve 214 for applying and draining pressure from pistons 108 and 110 respectively, depending on whether the nozzles are filling or emptying.

It should be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the spirit or scope of this novel concept as defined by the following claims.

What is claimed is:

1. A fuel control for a turbine type powerplant having a 'burner section that includes a plurality of burner se-gments, each segment having its own fuel connecting line,

(a) a distributor valve for sequentially filling said fuel connecting lines with fuel prior to interconnecting said fuel connecting lines with additional fuel whose quantity has been precalculated commensurate with desired burning characteristics,

(b) said distributor valve having a rotatable generally cylindrical shaped member,

(c) a plurality of fixed ports circumferential spaced adjacent said rotatable member each of which communicate with each of said fuel connecting lines,

(d) control means for imparting movement to said rotary member for sequentially and successively registering a radial fuel feed passage in said rotary member with each of said ports and an opening in said rotary member communicating with the ports succeeding the port being in register relation with the radial passage.

2. A fuel control as claimed in claim 1 including a control bore formed in said rotary member interconnecting said radial passage and an orifice formed in said rotary member which orifice is in serial flow relation to said radial passage.

3. A fuel control as claimed in claim 2 including means for varying the area of said orifice.

4. A fuel control as claimed in claim 3 wherein said means for imparting rotary movement includes a hydraulic actuated piston and means interconnecting said piston and said rotatable member.

5. A fuel control as claimed in claim 4 including a pilot lever, means responsive to the position of said pilot lever for controlling the position of said hydraulic actuated piston and means responsive to the pressure drop across said orifice for rendering said hydraulic actuated piston inoperative until a predetermined value of said pressure drop has been obtained.

6. A fuel control as claimed in claim 5 wherein said control means includes cam means, another hydraulic piston for imparting movement to said cam means, a pilot valve hydraulically coupled to one side of said other hydraulic piston, a flow line connected to the other side of said hydraulic piston and latching means regulating the flow of hydraulic fluid in said flow line, and means for actuating said latching means.

7. A fuel control as claimed in claim 6 wherein said flow regulating means respond to the pressure drop across said orifice.

8. A fuel control as claimed in claim 7 including a feedback connection interconnecting said cam and said pilot valve for returning said pilot valve to its null position in time relation with said latching means.

9. A fuel control as claimed in claim 5 wherein said pressure drop responsive means includes a single sensor monitoring singularly the ow of fuel during said lling of each of said fuel connecting lines.

References Cited UNITED STATES PATENTS 735,196 8/1903 Barkowsky 431-280 2,106,310 l/1938 Warrick 43l-280X 2,335,085 11/1943 Roberts 431--280X 8 Redding 60-261 Crim 60-39.74UX

Karen 60-39.74X

Townsend 431--280X Moreau 431-280X Rogers et al. 60-237 Andrews 60-241 Rimmer 60-241X AL LAWRENCE SMITH, Primary Examiner U.S. Cl. X.R. 

